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Relationships ​

Ma'lumotlarni bazaga saqlaganda modellar bir-biriga bog'lanishi mumkin.

Birga ko'p bog'lanish ​

Masalan mahsulot qaysi kategoriyaga tegishli ekanligi haqida ma'lumotni saqlash uchun mahsulot modeli kategoriya modeliga bog'lanadi.

python
from django.db import models

class Kategoriya(models.Model):
    nomi = models.CharField(max_length=50)
    
class Mahsulot(models.Model):
    kategoriya = models.ForeignKey(Kategoriya, on_delete=models.RESTRICT)
    nomi = models.CharField(max_length=50)
    narxi = models.IntegerField()
    tavsifi = models.TextField()
from django.db import models

class Kategoriya(models.Model):
    nomi = models.CharField(max_length=50)
    
class Mahsulot(models.Model):
    kategoriya = models.ForeignKey(Kategoriya, on_delete=models.RESTRICT)
    nomi = models.CharField(max_length=50)
    narxi = models.IntegerField()
    tavsifi = models.TextField()

Mahsulot modeli kategoriya fieldi orqali Kategoriya modeliga bog'landi.

Bu bog'lanish birga ko'p bog'lanish deyiladi va bunday usulda bog'lash uchun ForeignKeydan foydalaniladi.

Birga ko'p bog'lanish deb bitta obyektga bir nechta obyekt bog'lanishiga aytiladi.

Masalan, meva nomli kategoriyaga olma, nok, banan, olcha kabi mahsulotlar bog'lanishi mumkin.

Ko'pga ko'p bog'lanish ​

Yuqoridagi birga ko'p bog'lanishda olma, nok, banan, olcha faqat meva kategoriyasiga bog'lanishi mumkin.

Ko'pga ko'p bog'lanish holatida esa boshqacha bo'ladi. Masalan universitetdagi domla va talabalarni olaylik.

Bitta domlaga bir nechta talaba darsga kiradi. Lekin talaba ham o'z vaqtida bir nechta domlaga darsga kiradi.

Ya'ni bitta domlaga bir nechta talaba to'g'ri kelsa, bitta talabaga ham bir nechta talaba to'g'ri keladi.

Buning modeli djangoda:

python
from django.db import models

class Talaba(models.Model):
    ismi = models.CharField(max_length=40)
    familiyasi = models.CharField(max_length=40)

class Domla(models.Model):
    ismi = models.CharField(max_length=40)
    familiyasi = models.CharField(max_length=40)
    talabalari = models.ManyToManyField(Talaba)
from django.db import models

class Talaba(models.Model):
    ismi = models.CharField(max_length=40)
    familiyasi = models.CharField(max_length=40)

class Domla(models.Model):
    ismi = models.CharField(max_length=40)
    familiyasi = models.CharField(max_length=40)
    talabalari = models.ManyToManyField(Talaba)

TIP

ManyToManyField ko'pga ko'p bog'lanish holatida ishlatiladi.

Birga bir bog'lanish ​

Bunga quyidagicha misol keltirish mumkin. Bitta pasport faqat bitta odamga tegishli bo'lishi mumkin va shu bilan birga bitta odamda faqat bitta pasport bo'lishi mumkin. Bu holat birga bir bog'lanish deyiladi.

python
from django.db import models

class Odam(models.Model):
    ismi = models.CharField(max_length=40)
    familiyasi = models.CharField(max_length=40)
    yoshi = models.IntegerField()
    
class Pasport(models.Model):
    odam = models.OneToOneField(Odam, on_delete=models.RESTRICT)
    seriyasi = models.CharField(max_length=20)
    olingan_sana = models.DateField()
from django.db import models

class Odam(models.Model):
    ismi = models.CharField(max_length=40)
    familiyasi = models.CharField(max_length=40)
    yoshi = models.IntegerField()
    
class Pasport(models.Model):
    odam = models.OneToOneField(Odam, on_delete=models.RESTRICT)
    seriyasi = models.CharField(max_length=20)
    olingan_sana = models.DateField()